Apparatus for producing milk of lime



July 10, 1951 R, s, WALKER 2,559,691

APPARATUS FOR PRODUCING MILK 0F LIME Original Filed Aug. 24, 1945 Patented July 10, 1951 APPARATUS FOR PRODUCING MILK OF LIME Robert S. Walker, Allentown, Pa., assignor to Traylor Engineering & Manufacturing Company, Allentown, Pa., a corporation of Delaware Original application August 24, 1945, Serial No. 612,459. Divided and this application January 16, 1948, Serial No. 2,638

3 Claims. 1

This invention relates to apparatus for producing milk of lime and has as a main object to provide improved control whereby a product having the desired physical properties as to particle size and shape, and hence settling rate, is obtainable. To this end, the new apparatus includes means for eiiecting a slaking step whereby a fully slaked lime of a putty-like consistency, substantially incapable of self-flow, is produced, and a diluting step whereby a milk of desired consistency is produced. In the slaking step, the slaking temperature is maintained substantially constant, the temperature being selected in accordance with the physical properties, as to particle size and shape, desired in the product. Maintenance of the slaking temperature is best accomplished by utilizing the cooling effect of the slaking liquid and adjusting the liquid supply in dependence upon the temperature existing in the slaking zone.

In the accompanying drawing there is shown, partly in elevation and partly in vertical longitudinal section, suitable apparatus in accordance with the invention.

In the drawing, reference numeral it designates a cylindrical shell or drum disposed On a generally horizontal axis and mounted for rotation on rings and rollers as at I! and E2. The drum is rotatable, as here shown, by means of an electric motor l3 which, through a speed reducer it, drives a pinion 55 which engages a ring gear it fixed to the drum.

At the head end of the drum there is secured thereto an annular inwardly projecting flange ll defining a central circular opening 18 with its center on the drum axis, and an outwardly flared annular flange [9 projects from the outer surface of flange ll. At its foot end the drum has, a conical outwardly tapering extension 28 defining a circular end opening 2! Whose center is On the axis of the drum. The lowest point of opening 2! is higher than the lowest point of opening I8 so that liquid at a certain depth in the drum will overflow through opening ill but not through opening 2!. The extension 20 is provided with an internal spiral 722.

Reference numeral 23 designates a cylindrical shell or drum mounted concentrically within drum IQ for rotation therewith and in inwardly spaced relation thereto so that an annular space 24 exists between the two drums. The drum [0 is provided in space 24 with an internal spiral 25 whose inner edge is spaced outwardly of drum 23, except that, if desired, the spiral can be provided at intervals with radially inwardly projecting spokes forthe support of the inner drum. At its head end the inner drum is provided with an outwardly tapering inwardly projecting conical flange 26 which defines a circular opening 21 concentric with opening IS, the outer end of flange 26 being spaced radially inwardly of the edge of opening i8 50 that an annular space exists between flanges I! and 2B. The foot end of the inner drum terminates short of extension 20.

Reference numeral 28 designates a feed spout projecting into the head end of the inner drum through opening 21. As here shown, the spout extends from a rotary feeder 28 surmounted by a lime hopper iii. The hopper may be in receiving relation to a storage bin or to the output end of a lime kiln. The particular arrangement in this respect is immaterial except that means should be provided for effecting a fairly constant supply to the inner drum.

Reference numeral 39 designates a pipe extending from a source of any suitable slaking liquid into the head end of the inner drum through opening 2? so that slaking liquid is suppliable immediately adjacent the lime input. Reference numeral 3| designates a regulating valve in pipe 39 controllable by an electrically operated motor 32 which, through a connection 33, is under the control of an instrument 3% having a manually settable pointer 35 cooperating with a temperature scale 35. Reference numeral 37 designates a thermocouple supported in the inner drum inwardly of the point of lime and liquid supply and preferably below the level of the material in the drum so as to be directly afiected by the temperature of the material. The thermocouple is in connection with instrument 34 through wires 38 and 39.

Reference numeral 40 designate a pipe leading from a source of suitable diluting liquid into extension 20 through opening 2!. A regulating valve 4| in pipe 40 is controllable by an electrically operated motor l2 which, through a connection 43, is controllable by an instrument 44 having a manually settable pointer 45 cooperating with a temperature scale 46. Reference numeral 41 designates a thermocouple disposed below flange l9 somewhat outwardly thereof and in connec-' tion with instrument 44 through wires 48 and 49. Reference numeral 50 designates a tank disposed below the thermocouple.

In the operation of the apparatus, lime is continuously fed into the inner chamber and slaking liquid is continuously supplied throu h ipe 30 as controlled by valve 3!. Depending on the physical characteristics desired as to particle size and shape, a certain temperature should be subs .thermocouple 37.

stantially maintained in the slaking chamber. No definite temperatures of general application can be specified due to the variables encountered, but as soon as the plant is set up, the required temperature can be readily determined. It will be somewhere between 150 and 200 F. and, for example, may be 186 F. In that case, instrument 34 is set at 186 with valve 3| adjusted to supply the amount of slaking liquid normally required to maintain this temperature. The slaking liquid will ordinarily be at a substantially constant temperature for any given period although there may, of course, be a rather wide variation between summer and winter temperatures. This will be taken care of in a manner to be later explained. In any event, if under the assumed circumstances, the slaking temperature varies in either direction from 186 F., instrument 34 will cause appropriate operation of motor 32 so that more or less of the slaking liquid will be supplied and correction will be made.

In order to obtain the required cooling effect, it is always necessary to supply more slaking liquid than the minimum required for the completion of the reaction and, consequently, the resultant will always be of a putty-like consistency instead of in dry condition. The resultant, or reaction product, which is substantially incapable of self-flow, moves toward the foot end of the slaking chamber under the influences of the rotation of the drum 33 and of the continued feed of lime and liquid at the head end. The chamber is long enough with respect to the rate of feed so that the reaction will be completed therein and the product will break down to the putty-like consistency above mentioned. This consistency will, of course, vary under difierent conditions. For example, if the slaking liquid is relatively cold, less will be required for cooling than as though it were relatively warm, the quantity of fed lime remaining constant. However, there is always an excess of liquid beyond the minimum required for the reaction but the excess will be far short of that required to produce a milk and, hence, the slaked lime will emerge from the foot end of the sled:- ing chamber in the aforesaid putty-like consistency and will drop into the outer chamber defined by drum Iii.

Depending upon the consistency required in the milk of lime, valve 1! will be adjusted for the supply of the necessary amount of diluting liquid. The diluting liquid and the slaked lime will flow toward the head end of the outer drum by the hydraulic head resulting from the fact that the opening 2| is at a higher elevation than the opening 18. The spiral exerts a mixing action on the flowing material, and a well dispersed product overflows through opening Hi and over flange it to tank 50, the overflow bathing the The overflow is tested and valve M is adjusted until the overflow has the desired consistency. If there is a marked change at any time in the temperature of the slaking liquid, this will be taken care of by appropriate manual adjustment of valve lil so that the consistency of the milk is maintained. Ordinarily it will be found that the slaking liquid and the diluting liquid will be supplied in approximately the ratio of l to 3.

The bottom of the inner drum is below the overflow level in the outer drum but there is a sufficient depth of material in the inner drum to prevent any excessive infiow of diluting liquid.

If the rate of feed of the lime should vary,

the supply of slaking liquid is automatically appropriately varied. For example, if the rate of feed should diminish, less slaking liquid will be required for the proper cooling effect and valve 3! will be correspondingly closed. Since the volume of slaked lime is thus diminished, less diluting liquid will be required, but since the supply of diluting liquid is at this time constant, there will be a greater cooling effect on the milk of lime which is being produced. Instrument 44 was originally set at the temperature of the adjusted milk of lime output and when the output now becomes colder, the instrument acts to cause motor 42 to close valve 4! sulficiently so that the normal temperature, and hence consistency, of the output will be re-established. Inasmuch as corrections are not instantaneous, the tank 50 should be of sufliciently large capacity so that the consistency of the milk of lime therein will average out.

The spiral 22 acts to discharge grit and like foreign matter through opening 2|. As shown in the drawing, the pitch of the spiral 22 is such that the drum is normally rotated in a counterclockwise direction, when looking toward the right hand or head end thereof. The spiral rib 25 is similarly pitched, with the result that grit, tailings, and other foreign matter, precipitated from the milk of lime flowing toward the right will be positively and mechanically fed toward the left, where it will be picked up by the rib 22 and discharged through the opening 2i as noted above. Thus, the method of the present invention constitutes a combined continuous slaking and classifying method.

It will be understood that the described apparatus is illustrative of apparatus in accordance with the invention but that the invention is by no means limited thereto but extends to other arrangements coming within the terms of the following claims.

The present application is a division of my application Serial No. 612,459, filed August 24. 1945, now abandoned.

1. Apparatus for producing milk of lime, comprising a generally horizontally extending drum mounted for rotation about its longitudinal axis, said drum having an inner peripheral flange at its head end defining a discharge opening and having an annular wall at its foot end defining an opening whose lower edge is above the level of the lower edge of the head end opening, a second drum having an imperforate cylindrical side wall disposed concentrically within the first in peripherally spaced relation for rotation therewith. said second drum having an inner peripheral flange at its end adjacent the head end of the first drum defining a feed opening disposed inwardly of said discharge opening and its other end terminating short of the foot end of the first drum, the lower edge of the feed opening of the second drum being above the level of the lower edge of the discharge opening of the first drum and there being an annular discharge outflow space between the end flanges of the two drums, means for continuously delivering lime and slaking liquid through the feed opening into the head end of the second drum, said second drum discharging slaked limit from its said other end into the first drum, and means for continuously supplying a diluting fiuid to the foot end of the first drum whereby to produce a milk which is discharged through the head end opening of the first drum.

2. An apparatus for slakin and classifying 5. lime, comprising elongated horizontally arranged, circumierentially imperforate, inner and outer drums mounted for conjoint rotation on a horizontal axis, the drums having concentric openings at their head ends and the inner drum being unrestricted and open at its foot end for the direct discharge of material therefrom into the outer drum, said outer drum comprising a tapering section at its foot end terminating in a central opening of reduced diameter at an elevation above the openings at the head end, a spiral rib projecting inwardly from the outer drum toward the inner drum in spaced relation to the latter, a second spiral rib of similar pitch to the first, projecting inwardly from said taperin section, means for rotating the drums in a direction with respect to the pitch of said ribs that they tend to move material engaged thereby toward the foot end opening, means for delivering lime and slaking liquid to the head end of the inner drum for movement therethrough into the outer drum through the open, foot end of the inner drum, and means for introducing diluting liquid into the outer drum through the opening at the foot end, for admixture with the material received in the outer drum from the inner drum for flow against the force of said spiral ribs for discharge at the head end of the outer drum, said spiral ribs serving to convey grit and tailings precipitated from the flowing material, toward the opening at the foot end of the outer drum for discharge therethrough.

6 3. Apparatus in accordance with claim 2, in-

cluding means positioned inwardly beyond the lime and slaking liquid delivering means, for determining the temperature of the material in the inner drum and means responsive thereto for controlling the delivery of slaking liquid to the head end of the inner drum.

ROBERT S. WALKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS France July 19, 1920 

1. APPARATUS FOR PRODUCING MILK OF LIME, COMPRISING A GENERALLY HORIZONTALLY EXTENDING DRUM MOUNTED FOR ROTATION ABOUT ITS LONGITUDINAL AXIS, SAID DRUM HAVING AN INNER PERIPHERAL FLANGE AT ITS HEAD END DEFINING A DISCHARGE OPENING AND HAVING AN ANNULAR WALL AT ITS FOOT END DEFINING AN OPENING WHOSE LOWER EDGE IS ABOVE THE LEVEL OF THE LOWER EDGE OF THE HEAD END OPENING, A SECOND DRUM HAVING AN IMPERFORATE CYLINDRICAL SIDE WALL DISPOSED CONCENTRICALLY WITHIN THE FIRST IN PERIPHERALLY SPACED RELATION FOR ROTATION THEREWITH, SAID SECOND DRUM HAVING AN INNER PERIPHERAL FLANGE AT ITS END ADJACENT THE HEAD END OF THE FIRST DRUM DEFINING A FEED OPENING DISPOSED INWARDLY OF SAID DISCHARGE OPENING AND ITS OTHER END TERMINATING SHORT OF THE FOOT END OF THE FIRST DRUM, THE LOWER EDGE OF THE FEED OPENING OF THE 